What is colour

Colour is simply light of different wavelengths and frequencies and light is just one form of energy that we can actually see that is made up from photons.

We all live in a world where at some point, colour will be a part of, and effect us in our every day lives. Colour in everyday life is very diverse, from knowing that a fruit is ripe to eat, to understanding how Colour can affect our moods: Blue can be Calming - Red can make you tense.

We are all surrounded by electromagnetic waves of energy of which colour is just a small part.

Colour Properties - the colour spectrum

The visible spectrum of colour as we see it, consists of seven main colours:

The retinas in our eyes though have three types of colour receptors in the form of cones. We can actually only detect three of these visible colours - red - blue and green. These colours are called additive primaries. It is these three colours that are mixed in our brain to create all of the other colours we see... how clever we are!

The wavelength and frequency of light we see, also influences the colour we see. The seven colours of the spectrum all have varying wavelengths and frequencies. Red is at the lower end of the spectrum and has a higher wavelength but lower frequency to that of Violet at the top end of the spectrum which has a lower wavelength and higher frequency.

Where does colour come from?

Colour simply comes from light. Sunlight of course is the main source that that we are all familiar with. Using a prism, we can 'extract' the colours from white light - ie. sunlight.

When light from the sun passes through a prism, the light is split into the seven visible colours by a process called 'refraction'.

Refraction is caused by the change in speed experienced by a wave of light when it changes medium.

Light energy

The amount of energy in a given light wave is proportionally related to its frequency, thus a high frequency light wave has a higher energy than that of a low frequency light wave.

Colour is made up of different Wavelengths and Frequencies

Each colour has its own particular wavelength and frequency. Each colour can be measured in units of cycles or waves per second.

If we can imagine light traveling in waves like that in an ocean, it is these waves that have the properties of wavelength and frequency. A wavelength is the distance between the same locations on adjacent waves. As an example; an ocean full of waves, that were 10 meters apart, could be said as, having a wavelength of 10, whereas an ocean of waves that were 30 meters apart would be said as having a wavelength of 30.

The same applies to light. The colour RED has a wavelength of around 700 nanometers long - one wave spans only 7 ten millionths of a meter! Whereas, Violet has a much shorter wavelength, so each violet wave would span a much shorter distance.

Waves of Energy

Within the Universe, positive and negative charges (waves of energy), are constantly vibrating and producing electromagnetic waves traveling at an incredibly high speed.(186,000 miles per second, the speed of light.)

Each of these waves has a different wavelength and speed of vibration. Together they form part of the electromagnetic spectrum.

Light travels in waves. A wavelength is the distance between the same locations on adjacent waves.

Frequency

The frequency of a wave is determined by the number of complete waves, or wavelengths, that pass a given point each second.

The colour RED for example, has a frequency of around 430 trillion vibrations a second, whereas Violet has a much higher frequency, so each violet wave would pass a given point much quicker than the colour RED. All light travels at the same speed but each colour has a different wavelength and frequency.

Frequency of waves

To try and explain the frequency of colour and light a little further, imagine that an ocean with waves that are 10 meters apart that crash on the shore every 5 seconds could be classed as having a frequency of 5, whereas an ocean of waves 10 meters apart that crashed on the shore every 10 seconds, would be classed as having a frequency of 10. The more frequent the waves, the HIGHER the frequency.

It is these different wavelengths and frequencies that cause the different colours of light to separate and become visible when passing through a prism. This can be looked upon in the same way that radio waves have different frequencies and wavelengths, certain stations can only be listened to at a particular frequency or wavelength. So the colour blue - say, can only be visible at a particular frequency and wavelength range.

The higher the frequency, of the colour, the closer together the waves of energy are.